Electromagnetic actuator and switch mechanism and method of operation thereof



March 3, 1959 E. P. LARSH 2,875,310

ELECTROMAGNETIC ACTUA AND swI'rcH HANISM AND METHOD OF RATION THERE Filed Sept. 18, 1956 3 Sheets-Sheet 1 EVERETT BY 7W ;7wlwf A #0 rneys 2,876,310 I'ICH MECHANISM AND E. P. LAR'SH TUATOR AND sw OF OPERATI March 3, 1959 ON THEREOF ELECTROMAGNETIC AC METHOD Filed Sept. 18, 1956 3 Sheets-Sheet 2 INVENTOR. EVERETT e LARSH Attorneys March 3, 1959 E E. P. LARSH 2,876,310

ELECTROMAGNETIC ACTUATOR AND SWITCH MECHANISM AND METHOD OF OPERATION THEREOF Filed Sept. 18, 1956 3 Sheets-Sheet 3 INVENTOR. EVERETT P. LARS H Attorneys United States Patent ELECTROMAGNETIC ACTUATOR AND SWITCH MECHANISM AND METHOD OF OPERATION THEREOF Everett P. Larsh, Dayton, Ohio Application September 18, 1956, Serial No. 610,523 Claims. (Cl. 200-404) This invention relates to an actuator, especially one in which an axial thrust is converted into rotary motion, and to a control unit, and, in particular, to an electromagnetically-operated unit of this nature.

More particularly still, the present invention relates to an electromagnetically-Operated actuator having particular merit in connection with electrical contact elements, thus forming, in combination, an electric relay. This invention, however, is not limited to a relay, *but may also be used to turn valves, latches, levers, clutches, brakes, etc.

Electrical relays are an extremely widely used component in electrical control circuits and the like, and in practically every case where an electric relay is employed it is important for it to be a reliable trustworthy unit capable of a great many repetitive cycles without failure. This is particularly true in control circuits for automatized systems because successful repetitive operation is absolutely essential for the system to be operative. The primary object of the present invention is the provision of an improved electromagnetic actuator especially adapted for use in connection with the control of the contact elements of relays, although not necessarily limited thereto.

A further primary object of the present invention is the provision of an electromagnetic control unit adapted for use with the contact elements of a relay or the like which provides for positive movement of the contact elements at all times.

Another object of the present invention is the provision of an electromagnetic control unit which is compact and which can, therefore, be mounted in the minimum of space.

A further object of the present invention is the pro vision of an electromagnetic unit which is eflicient in operation, and in connection with which the results are predictable within close limits.

A particular object of the present invention is the combination of a rotary electromagnetic actuator and contact elements controlled thereby in which the contact elements are brought together positively and under pressure and with a wiping movement whereby the contacts remain clean at all times.

A still further object of the present invention is the provision of an improved structure for converting magnetic thrusts into torque thereby causing rotary movementof the movable member of an electromagnetic unit;

Another object of this invention is the provision of a rotary magnetic actuator that is readily adaptable to a plurality of work situations.

A still further object of this invention is the provision of a rotary electromagnetic actuator of the nature referred to wh'ich can successfully be operated on alternating current, thus eliminating the need for the provision of direct current, as, for example, by rectifiers. These. and other objects and'advantages of this invention will become more apparent upon reference to the following specification taken in connection with the accompanying drawings, wherein:

Figure 1 is a perspective view showing an electro magnetic actuator unit according to the present invention and contact elements controlled thereby assembled in combination with an overload relay to provide for an electric contactor or relay;

Figure 2 is a perspective view showing the arrangement of the contact elements in the contact section of the unit;

Figure 3 is an exploded perspective view showing the elements of the unit, by means of which an axial thrust is converted into rotary movement upon energization of the unit;

, Figure 4 is a vertical sectional view indicated by line 4-4 on Figure 2 showing the manner in which the stationary and movable portions of the unit are resiliently interconnected;

Figure 5 is a bottom plan view of the unit showing the overload portion thereof;

Figure 6 is a perspective view showing more in detail the construction of the overload section of the unit;

Figure 7 is a perspective view showing the bimetallic strips and contact elements associated with the overload contact points of the present invention;

Figure 8 is a plan sectional view indicated by line 8-8 on Figure 2 showing the arrangement of the rotor and stator and the several contact elements carried thereby and the contact points associated therewith;

Figure 9 is a View showing one of the shield or guard members that surrounds the electrical section of the unit, which has a protuberance on one side with apertures therein so that leads can be brought into the electrical section through the shield or guard;

Figure 10'is a perspective view similar to Figure 3 but showing the manner in which the helical grooves or slots could be provided in the telescoping sleeves at two levels instead of one, thereby to provide a more rigid support for the rotor of the unit;

Figure 11 is a developed view showing the cam arrangement associated with the overload section of the unit;

Figure 12 is a diagrammatic view illustrating the wiping action of the contacts with the contact points as they open and close as viewed in plan; and

Figure 13 is a view similar to Figure 12 except look ing in at the contact points from the back of the movable one thereof.

The particular embodiment of the present invention, which is shown in the drawings, is a double-throw switch or relay having a thermal overload unit associated therewith.

The unit consists of the electromagnetic actuator section, the electrical contact section that is controlled by the electromagnetic actuator, and the thermal overload section which is in circuit with the electrical contact section, but which is otherwise independent of the structure of the contact or relay.

The electromagnetic section comprises a first stationary core element 10 mounted in the upper end of a downwardly Open casing part 12 and having an annular recess 13 in which there is mounted the solenoid coil 14.

The core element 10 may consist of shaded pole sections (not shown) provided for in any of several well known manners whereby energization of the solenoid coil 14' by alternating current will provide for a more or less steady magnetic attraction of the magnetic armature, and in this manner eliminate chattering and vibrating which sometimes accompanies the operation of alternating current magnetic devices.

Arranged in spaced opposedrelation 'to core element is a second stationary core element having an upwardly opening annular recess therein, within which is mounted the solenoid coil 16. The element 15 has shaded pole portions similar to those described in connection with core element 10 and for the same reason.

The core elements are retained in fixed spaced relation by a spacer ring 17 therebetween, and are secured to each other in any suitable manner, such as by attachment of both of the core elements to the cover member 12.

Disposed in the space between core elements 10 and 15, and thinner in the axial direction than the space between the core elements, is a magnetic armature disc 18 fixed to the upper end of a shaft 19 that extends downwardly. through lower core element 15.

At its lower end shaft 19 has fitted to the spline-like end portion thereof a rotor comprising one or more blocks of insulating material 20 and 21 held in place by a snap ring which carry in circumferentially spaced relation, and extending radially therefrom, the contact elements 22, each of which has fixed thereto the contact points 23'. The contact elements 22 are of a resilient nature to develop a wiping action between the contact points 23 carried thereby and the fixed contact points which they engage, which will become apparent hereinafter.

As will be seen in Figure 8, there may be four of the contact elements 22 uniformly spaced about the rotor portion of the electrical section of the unit. The rotor portion may, of course, consist of as many of the said contact elements mounted in the blocks 20 and 21 as space permits and the job requires.

The electrical section of the unit also comprises a stator portion made up of the annular insulating blocks 24 and 25 which surround the rotor, and which blocks carry fixed contact elements 26 having thereon the contact points 27 adapted for engagement by the contact points 23 of the contact elements of the rotor.

The contact elements 26 may advantageously be in the form of substantially L-shaped metallic strips, with one leg thereof extending peripherally about the outside of the pertaining stator block whereby the clamp screws 28 can be carried thereby for securing to the stationary elements the wires leading to the electrical section of the unit. These wires are brought into the unit through apertures 29 formed in one wall of the shield or guard member 30, which, together with a corresponding shield or guard member 31 assembled therewith, surrounds and encloses the electrical section of the unit.

Figure 9 shows a plan view of the rotor shield member through which the wires are carried into the stationary contact elements of the unit showing the space provided at the apertured side to distribute the wires.

In order to provide a normally centered position of the rotoi' within the stator there extends between the rotor and stator the spring elements 32 which have their ends seated in recesses in the blocks making up the stator and rotor, and which have their intermediate portions extending between the stator and rotor so formed as to be resiliently defiectable in all directions, whereby the rotor can both rotate and reciprocate relative to the stator while the said springs set up a restoring force of a predetermined amount tending to move the rotor back to a neutral position.

The novel arrangement of the present invention for causing turning movement of the rotor upon axial movement of the armature disc 18 consists of an inner sleeve 33 secured to shaft'19, and an outer sleeve 34 fitted into a bushing 35 mounted fixedly in the center bore of the core element 15.

Sleeves 33 and 34 have therein the registering helical slots, grooves or recesses 36 and 37, and in each pair of registering slots there is located a ball 38. Each ball 38 extends into both of the slots pertaining thereto and fits closely therein and serves precisely to locate the shaft 19 angularly for each axial position thereof. This is a positive, exact location in both directions of movement of shaft 19 and is not dependent upon any restoring force of the springs between the stator and rotor acting circumferentially.

The sleeves 33 and 34, shown in perspective in Figure 3, may have a single slot on each side thereof, or each sleeve may have slots at two different levels if so desired, as illustrated in Figure 10, whereby the rotor is guided by the ball and slot arrangement in an exact path at all times. With an arrangement of this nature the only control necessary on rotor 18 is a spring force tending normally to center the rotor when the electromagnetic section of the unit is de-energized.

The outer sleeve 34 is preferably either split or formed by rolling up a fiat piece. This permits the outer sleeve to be opened to permit its assembly with the inner sleeve and the balls 38 so that a close fit between the two sleeves will be had. After assembly any suitable means may be provided for preventing relative rotation between the sleeves and the parts on which they are supported. The outer sleeve, for example, may be a light press fit in its surrounding bushing, while the inner sleeve has a slot at the bottom end to engage a key in shaft 19.

At the extreme bottom of the unit is the overload section previously referred to, and which overload section is of the thermally-sensitive type that includes normally closed contacts that may be connected in circuit with one or more of the contacts of the electrical section of the unit.

The overload unit comprises an insulating body part 40, and mounted therein in spaced relation are the bimetallic contact elements 41 and 42 which are of the snap-action type, which is to say, they will remain curved either concave upwardly or concave downwardly until moved to the opposite position.

The bimetallic elements 41 and 42 are retained in place by the rivets .43 and 44 that secure them to the body part 40, and which rivets also secure, in fixed heat-conducting relation to the bimetallic elements, the heat conductor strips 45 and 46. These heat conductor strips are associated with the heat generating elements 47 and 43 in Figure 7, which are connected in circuit so as to be sensitive to the current flow that is to be regulated by the overload unit.

The rivets are electrically interconnected and, thus, the bimetallic elements are also interconnected by a conductive strap 49 extending between the rivets on top of the overload section. The bimetallic elements could, of course, remain separate and independent and each control a different circuit if desired.

Each of the bimetallic strips 41 and 42 has a longitudinal slot therein to one side of the rivet, and the one side of the bimetallic strip is fixed in place by the pertaining rivet, and the other side of the bimetallic strip extends into a groove 50 in a control cam 51 that extends out through bottom cover plate 52 and terminates in a knob 53.

Groove 50 is of sufiicient axial length to provide for relatively free movement of the bimetallic strips therein and comprises spaced rises extending into the groove pertaining to each of the bimetallic strips, which will best be seen as to their location and function in Figure 11 which is a developed view of one side of the cam.

In Figure 11 the cam will be seen to comprise a rise 54 which can be brought into operative relation with the adjacent bimetallic strip to prevent the strip from flexing under the influence of heat conducted thereto from the heat-conductive strip 45. Under these circumstances the overload relay will not snap open and it is said to be in ofi position.

As illustrated in Figure 11 the cam is in its on position and the bimetallic elementsare free to snap to their open position when heated. When the elements do snap to'their open position they occupy about the position illustrated by the dot-dash lines at 55, and when in this position the bimetallic elements can be reset by rotating the cam to its reset position, at which time the cam rise 56 flexes the bimetallic elements until they snap back to their contact-making position.

7 As has been mentioned, the core elements may be fixed together in any suitable manner. The entire assembly may be fixed to a support by thescrews 60, shown in Figure 1, while the electrical section and the overload section are fixed to the actuator section by the screws 62 which pass through bores provided in the units in regions not occupied by contact elements and where the stator blocks are solid from face to face.

A cover plate 64 may cover the overload section and this provides for a completely enclosed assembly.

It has been mentioned that the contact points in the electrical section of the unit have a positive wiping action which maintains them clean and in good operating condition at all times. This action is illustrated in Figures 12 and 13.

In Figure 12, at the left side thereof, a stationary contact S is shown being engaged by the movable contact M. This is the initial condition of engagement and occurs before the rotor has come to a complete halt.

The view at the left side of Figure 13 shows the same contact points in the same condition of engagement from the back of the movable contact point.

At the right side of Figure 12 the contact points are shown after the rotor has continued a short distance beyond its last-mentioned position and has come to a halt. At the right side of Figure 12 it will be noted that the contact element strip, by means of which the movable contact point is supported, is somewhat flexed andthat this causes a wiping or rubbing action of the movable contactpoint on the stationary contact point, which wiping action removes any dirt or deposits and tends to overcome any pitting or roughness of the contact points that might have been caused by sparking at the time of opening thereof.

The right side of Figure 13 shows the contact points from the back after they are fully engaged.

The particular relay structure described above is one in which the energizing of either one of the solenoid coils will bring about the closing of four lines. It will be understood, however, that there could be several stacks of the contact elements under the control of the electromagnetic actuator within the scope of the present invention and the same conditions which have been described would prevail.

Further, the arrangement of the present invention has been shown as double-acting with the rotor having a normally centered position, but it will be apparent that the unit could be single-acting if so desired, and that the rotor could be biased toward one contacting position and then moved into another contacting position or into a non-contacting position by energization of a solenoid coil.

Further, since the electrical section of the unit is substantially entirely independent of the electromagnetic actuator section, it follows that the electrical section could be replaced by something other than a set of electrical contacts should it be desirable. For example, latches, valves, and the like are all adapted for being controlled by a rotary electromagnetic actuator of the present invention.

The helical slots or grooves, in which the balls that generate the rotary motion are mounted, have been shown as being inclined at a certain angle and as having a uniform helix angle. It will be apparent, however, that the particular helix angle of these grooves or slots could be variable, with the amount of rotary motion desired, in view of the amount of axial movement that could be permitted the armature and shaft.

In certain instances, where a small amount of angular movement would be sufiicient, the helix angle of the groove or slots might be rather steep; whereas, in other cases where a larger angular'movement is desired, the

helix angle of the grooves or slots might be rather small.

Further, the helix angle has been shown to be uniform,

but it could be varying if so desired'whereby a different relationship would exist between axial and rotary movement at the beginning of the stroke of the armature than at the end thereof. .In this manner any desired pattern of torque characteristics could be obtained. For example, a high initial torque might be desired to initiate rotation 'of a valve, and the initial portion of the slots would thus have a steep helix angle. On the other hand, it might be desired for the rotor to be held firmly in its terminal position while maintaining a high pressure on the actuated member. In this case the final portion of the grooves or slots would have the steeper helix angle to obtain the effect referred to. Thus, by forming a portion of the grooves or slots at one helix angle and the remainder thereof at another helix angle, certain specified high torque conditions can be met without sacrificing any substantial amount of the total available rotary movement of the actuating member.

Operation In operation, the device of the present invention is normally in a centered position, with the armature located midway between the spaced core elements and with the rotor contact points located midway between the stator contact points. At this time the grooves or slots in the telescoping sleeves are radially aligned. Upon energization of either of the solenoid coils the armature will be attracted toward the core element associated with the energizing coil, and the axial thrust on the armature is converted into combined axial and rotary movement because of the balls extending into the aligned grooves. This movement of the armature, and the parts connected therewith, including the rotor, continues until the parts are halted, as by the rotor bottoming against the stator,

or the balls reaching the ends of the grooves in which 1 they are mounted.

This stopping of the rotor occurs after the rotor contact points have engaged and wiped into mating contact with the contact points of the stator. It will be noted that the movement of the rotoris at all times in a precise and controlled path, and that, further, upon de-energization of the energizing solenoid the rotor will return along precisely the same path under the influence of the centering springs referred to, and the relay is then ready for a new operative cycle.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and accordingly it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. An electromagnetically actuated switch comprising, a disc-like electromagnet, a disc-shaped armature in spaced relation with said electromagnet, a shaft connected with the armature and extending in the direction of the axis of said electromagnet, telescoping sleeves, one thereof being fixed to the shaft and the other to said electromagnet, registering slot means in said sleeves located in circumferentially spaced relation about the sleeves, balls fitted into said slots thereby supporting the shaft on the axis of the electromagnet and also causing simultaneous rotary and reciprocatory movement of the shaft upon energization and de-energization of the electromagnet, switch means detachably connected with said armature shaft, said switch means comprising a stationary member having stationary contact elements fixed to said electromagnet, a rotor connected with the shaft and carrying contact elements for bridging between pairs of the said stationary contact elements,'and spring means be: tween the rotary and stationary parts of the switch normally holding the rotary portion of the switch in a predetermined position.

2. In an electromagnetic switch arrangement of the nature described, spaced opposed annular electromagnets each having energizing coils and cores, a disc-shaped magnetic armature between the cores, a shaft connected with the armature extending through one of the cores on the axis thereof, telescoping sleeves one fixed inside said one of said cores and the other fixed to said shaft,- inclined slots in the sleeves in circumferentially spaced relation thereabout, balls located in the slots thereby to support the shaft on the axis of said one core and to cause rotary movement of the shaft upon reciprocation thereof, a switch rotor detachably mounted on the end of said shaft opposite the armature, contact means carried by said rotor and projecting radially therefrom, a stationary body fixed to said one core in surrounding relation to said rotor and carrying fixed contact members for engagement with the contact means on the rotor, and spring means associated with the armature shaft normally holding said armature in centered position between said electromagnets.

3. A switch device comprising, an electro-magnet, an armature in normally spaced axial alignment therewith having a shaft connected therewith and extending through said electro-magnet centrally thereof, a first sleeve fixed in said electro-magnet having inclined slots therethrough perpendicular to the surfaces thereof and in axially and circumferentially spaced relation thereabout, a second sleeve fixed about said shaft within said first sleeve in spaced relation thereto and having similar normally opposed inclined slots therethrough, and spherical elements arranged in said slots to radially engage and support said shaft relative said electro-magnet, a contactor rotor on said armature shaft havingcontact elements radially projecting therefrom, a fixed contactor body in containing relation thereto having mating contacts in normally spaced relation to cooperating contacts on said rotor whereby on energization of said electro-magnet said shaft will have a true axial and rotatory movement imparted thereto for firm positive wiping action as the contacts are made, the armature seating squarely to the electromagnet in the process thereof.

4. A switch device of the character described comprising, spaced opposed core members having energizing coil elements therein, a single armature normally in intermediate spaced relation to said core members, a shaft means connected to said armature and extending through one of said core members, a sleeve fixed to one of said core members having inclined slots therethrough in axially and circumferentially spaced relation thereabout, a similar sleeve fixed to said shaft means in radially spaced relation to said first sleeve, and ball elements radially connecting said sleeves and radially contained thereby in the opposed slots therethrough, a switch rotor on said shaft means having contacts projecting therefrom in spaced relation, a switch contactor body in fixed relation to said core members and alfording fixed mating contacts for said switch rotor contacts, and centering spring means resiliently connecting said rotor and switch contactor body to normally maintain said rotor contacts respectively in centered relation to adjacent pairs of mating contacts on the contactor body whereby on energization of one of said core members said armature will be attracted thereto and a balanced axial and rotatory movement of said shaft means will be effected to provide a direct positive wiping engagement of contacts in a direction in accordance with the direction of attraction of the armature.

5. A relay switch comprising, opposed core elements having energizing coils seated thereto, a single armature normally in intermediate spaced parallel relation to said core elements, a shaft means connected to said armature and extending through one of said core elements, radial containing means in axially and circumferentially spaced relation about said shaft means connecting and supporting said shaft means relative said one of said core elements, means defining opposed inclined slots therethrough respectively on said shaft means and said one of said core elements, said radial containing means being contained therein and effecting a balanced axial and rotatory movement of said shaft means on energization of one of said core elements, a contactor body having cylindrically spaced columns defining cylindrical sectors having contacts seated to the radial sides thereof and providing a central aperture therebetween in axial alignment with said core elements, a contactor rotor body connected to said shaft means and supported in the central aperture, said contactor rotor being split to provide opposed recessed slots therein seating the inner ends of radially projecting spring contactor elements therein, said spring contactor elements have aligned contacts to either side thereof, and centering spring means connecting said rotor and contactor body to normally center said contactor elements relative said column sides whereby on energization of a core element a positive wiping engagement of contacts is effected in a selective clockwise or counterclockwise direction.

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